Zeeman-slower, coil for a Zeeman-slower device and a method for cooling an atom beam

Abstract

A Zeeman-slower device, a coil for such a Zeeman-slower device, and a method for cooling an atom beam. The Zeeman-slower includes a cooling section including an inner passage extending along a longitudinal axis, the inner passage having a cross-section perpendicular to the longitudinal axis, wherein the area of the cross-section of the inner passage increases monotonously along the longitudinal axis at least in a part of the cooling section.

1. A Zeeman-slower comprising:
 a cooling section including an inner passage extending along a longitudinal axis, the inner passage having a cross-section perpendicular to the longitudinal axis, 
 wherein the area of the cross-section of the inner passage increases monotonously along the longitudinal axis at least in a part of the cooling section. 
 
     
     
       2. A Zeeman-slower of  claim 1 , wherein the cooling section extends along the longitudinal axis from an input end to an output end, wherein the area of the cross-section at the output end is at least 120% of the area of the cross-section at the input end. 
     
     
       3. A Zeeman-slower of  claim 1 , wherein the cross-section of the inner passage has a circular shape. 
     
     
       4. A Zeeman-slower of  claim 1 , further comprising a coil surrounding the inner passage to provide a magnetic field in the inner passage in the direction of the longitudinal axis, wherein the magnetic field decreases monotonically along the longitudinal axis and is substantially homogeneous in the cooling section in a plane perpendicular to the longitudinal axis. 
     
     
       5. A Zeeman-slower of  claim 4 , further comprising at least one extraction coil adjacent to an output end and arranged to produce a magnetic field, which is substantially different from the magnetic field in the inner passage near the output end produced by the coil surrounding the inner passage. 
     
     
       6. A Zeeman-slower of  claim 1 , further comprising a deflector configured to deflect at least a part of light impinging onto the deflector into the inner passage and inclined to the longitudinal axis. 
     
     
       7. A Zeeman-slower of  claim 6 , further comprising a reflective surface in at least parts of the inner passage, the reflective surface configured to receive light from the deflector and to reflect light into the inner passage inclined to the longitudinal axis. 
     
     
       8. A Zeeman-slower of  claim 6 , wherein the deflector is configured to deflect light into the inner passage producing a light energy distribution in the cross-section of the inner passage, the light energy distribution being rotationally symmetrical to the longitudinal axis. 
     
     
       9. A Zeeman-slower of  claim 6 , further comprising:
 a laser device emitting a laser beam on the deflector, the deflector configured to modulate an angle between the longitudinal axis of the at least one coil and the laser beam. 
 
     
     
       10. A Zeeman-slower of  claim 6 , wherein the deflector is configured to direct light onto the cross-section of the output end to illuminate an output end with a distribution of light energy covering at least a partial area of the output end. 
     
     
       11. A Zeeman-slower of  claim 1 , further comprising means for providing an atom beam that enters the inner passage through the input end and leaves the slower through the output end. 
     
     
       12. A coil having an inner surface configured to define the inner passage of the Zeeman-slower of  claim 1 , the inner surface comprising at least one reflective area adapted to reflect light into the inner passage. 
     
     
       13. A method for cooling an atom beam, comprising:
 providing a magnetic field; 
 emitting an atom beam into the magnetic field; 
 directing at least a part of a light beam onto the atom beam; and 
 providing an inner passage having a cross-section, which increases monotonously along a longitudinal axis, the inner passage configured to accommodate the atom beam, 
 wherein the emitting an atom beam includes emitting an atom beam along the longitudinal axis, the atom beam having a cross section substantially expanding in a direction perpendicular to the longitudinal axis. 
 
     
     
       14. A method of  claim 13 , wherein the area of the cross-section of the atom beam and/or of the inner passage is expanded in total at least about 20% along the longitudinal axis. 
     
     
       15. A method of  claim 13 ,
 wherein the providing a magnetic field comprises providing a magnetic field with a component parallel to the longitudinal axis, the longitudinal magnetic field component having a magnetic field strength decreasing along the longitudinal axis, the longitudinal magnetic field component being substantially homogenous in a plane perpendicular to the longitudinal axis, 
 the method further comprising: 
 providing an additional deceleration of the atom beam in a direction perpendicular to the longitudinal axes by directing the at least part of a light beam onto the atom beam in a direction inclined to the propagation direction of the atom beam. 
 
     
     
       16. A method of  claim 15 , wherein the directing at least a part of a light beam onto the atom beam comprises reflecting at least a part of the light beam onto the atom beam and inclined to the atom beam, at a location substantially displaced from the longitudinal axis. 
     
     
       17. A method for coating by carrying out the method of  claim 13 .